Bowser Path

You can inhale the green worm but this will end the fight and you'll receive no EXP. Now and then a Fawfulcopter will come on the scene. Inhale it and have the bros handle. If you don't, it will summon reinforcements.

SlamWatch the worm's head. He'll indicate the number and type of attacks. If his head motions up, he'll hop at you and you'll need to duck. If it motions forward, he'll charge and you'll need to punch. So, if he motions up once and twice forward you can expect to duck the first attack and punch the second. Landing a punch will cancel any further attacks for that round.

ReinforcementsNow and then a Fawfulcopter will show up on the top screen. Vacuum it up before it calls for Chain Chawful reinforcements.

Fawfulcopter

Jump to attack as hammer strikes will just miss. The Fawfulcopter has no attacks but will escape Bowser's stomach if the bros take too long to take him out.

Fawful Guy

These guys are too small for Bowser to worry about. Just stomp them in the field.

FlipHe will do a flip and land in front of one of the bros then flip again and try to land on that bro's head. Hit him with the hammer. Sometimes the Fawful Guy will pull out an umbrella before he starts his flips. This will slow his descent and change the timing. Be on your guard.

SpitSomething off screen will eat the Fawful Guy and spit him at one of the bros. A targeting curser will tell you which bro so hop the projectile and try to land on it to do a little damage.